Evaluation of optimal water flow and temperature in response to outdoor air temperature in plastic greenhouse with recirculated water curtain system

Abstract

This study evaluated the optimal supply water temperature and flow rate in response to the outdoor air temperature in order to maintain a target indoor air temperature and minimize the amount of energy required to reheat a recirculated water curtain in a plastic greenhouse. This paper proposed a multiple regression model that estimated the indoor air temperature using the outdoor air and the inlet water temperatures, as well as the water flow rate, as independent variables. We also established a multiple regression model that estimated the average amount of energy required to reheat the recirculated water curtain. To this end, the study analyzed and quantified a reasonable inlet water temperature and water flow rate in response to the outside air temperature using isothermal and iso-energy curves. The results indicated that maintaining a higher water flow rate was preferable to maintaining a higher inlet water temperature for cultivation purposes.